platform/core-impl/src/com/intellij/ide/plugins/cl/PluginClassLoader.java

/*
 * Copyright 2000-2013 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.intellij.ide.plugins.cl;

import com.intellij.diagnostic.PluginException;
import com.intellij.ide.plugins.PluginManagerCore;
import com.intellij.openapi.diagnostic.Logger;
import com.intellij.openapi.extensions.PluginId;
import com.intellij.util.containers.ContainerUtil;
import com.intellij.util.lang.UrlClassLoader;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import sun.misc.CompoundEnumeration;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.net.URL;
import java.util.Collection;
import java.util.Enumeration;
import java.util.List;
import java.util.ListIterator;

/**
 * @author Eugene Zhuravlev
 * @since 6.03.2003
 */
public class PluginClassLoader extends UrlClassLoader {
  private final ClassLoader[] myParents;
  private final PluginId myPluginId;
  private final String myPluginVersion;
  private final List<String> myLibDirectories;

  public PluginClassLoader(@NotNull List<URL> urls,
                           @NotNull ClassLoader[] parents,
                           PluginId pluginId,
                           String version,
                           File pluginRoot) {
    super(build().urls(urls).allowLock().useCache());
    myParents = parents;
    myPluginId = pluginId;
    myPluginVersion = version;
    myLibDirectories = ContainerUtil.newSmartList();
    File libDir = new File(pluginRoot, "lib");
    if (libDir.exists()) {
      myLibDirectories.add(libDir.getAbsolutePath());
    }
  }

  @Override
  public Class loadClass(@NotNull String name, final boolean resolve) throws ClassNotFoundException {
    Class c = tryLoadingClass(name, resolve);
    if (c == null) {
      throw new ClassNotFoundException(name + " " + this);
    }
    return c;
  }

  // Changed sequence in which classes are searched, this is essential if plugin uses library,
  // a different version of which is used in IDEA.
  @Nullable
  private Class tryLoadingClass(@NotNull String name, final boolean resolve) {
    Class c = loadClassInsideSelf(name);

    if (c == null) {
      c = loadClassFromParents(name);
    }

    if (c != null) {
      if (resolve) {
        resolveClass(c);
      }
      return c;
    }

    PluginManagerCore.addPluginClass(name, myPluginId, false);
    return null;
  }

  @Nullable
  private Class loadClassFromParents(final String name) {
    for (ClassLoader parent : myParents) {
      if (parent instanceof PluginClassLoader) {
        Class c = ((PluginClassLoader)parent).tryLoadingClass(name, false);
        if (c != null) {
          return c;
        }
        continue;
      }

      try {
        return parent.loadClass(name);
      }
      catch (ClassNotFoundException ignoreAndContinue) {
        // Ignore and continue
      }
    }

    return null;
  }

  @Nullable
  private synchronized Class loadClassInsideSelf(@NotNull String name) {
    Class c = findLoadedClass(name);
    if (c != null) {
      return c;
    }

    try {
      c = _findClass(name);
    }
    catch (IncompatibleClassChangeError e) {
      throw new PluginException(e, myPluginId);
    }
    catch (UnsupportedClassVersionError e) {
      throw new PluginException(e, myPluginId);
    }
    if (c != null) {
      PluginManagerCore.addPluginClass(c.getName(), myPluginId, true);
    }

    return c;
  }

  public boolean hasLoadedClass(String name) {
    Class<?> aClass = findLoadedClass(name);
    return aClass != null && aClass.getClassLoader() == this;
  }

  @Override
  public URL findResource(final String name) {
    final URL resource = findResourceImpl(name);
    if (resource != null) return resource;

    for (ClassLoader parent : myParents) {
      final URL parentResource = fetchResource(parent, name);
      if (parentResource != null) return parentResource;
    }

    return null;
  }

  @Nullable
  @Override
  public InputStream getResourceAsStream(final String name) {
    final InputStream stream = super.getResourceAsStream(name);
    if (stream != null) return stream;

    for (ClassLoader parent : myParents) {
      final InputStream inputStream = parent.getResourceAsStream(name);
      if (inputStream != null) return inputStream;
    }

    return null;
  }

  @Override
  public Enumeration<URL> findResources(final String name) throws IOException {
    final Enumeration[] resources = new Enumeration[myParents.length + 1];
    resources[0] = super.findResources(name);
    for (int idx = 0; idx < myParents.length; idx++) {
      resources[idx + 1] = fetchResources(myParents[idx], name);
    }
    return new CompoundEnumeration<URL>(resources);
  }

  @SuppressWarnings("UnusedDeclaration")
  public void addLibDirectories(@NotNull Collection<String> libDirectories) {
    myLibDirectories.addAll(libDirectories);
  }

  @Override
  protected String findLibrary(String libName) {
    if (!myLibDirectories.isEmpty()) {
      String libFileName = System.mapLibraryName(libName);
      ListIterator<String> i = myLibDirectories.listIterator(myLibDirectories.size());
      while (i.hasPrevious()) {
        File libFile = new File(i.previous(), libFileName);
        if (libFile.exists()) {
          return libFile.getAbsolutePath();
        }
      }
    }

    return null;
  }

  private static URL fetchResource(ClassLoader cl, String resourceName) {
    try {
      final Method findResourceMethod = getFindResourceMethod(cl.getClass(), "findResource");
      return (URL)findResourceMethod.invoke(cl, resourceName);
    }
    catch (Exception e) {
      Logger.getInstance(PluginClassLoader.class).error(e);
      return null;
    }
  }

  private static Enumeration fetchResources(ClassLoader cl, String resourceName) {
    try {
      final Method findResourceMethod = getFindResourceMethod(cl.getClass(), "findResources");
      return findResourceMethod == null ? null : (Enumeration)findResourceMethod.invoke(cl, resourceName);
    }
    catch (Exception e) {
      Logger.getInstance(PluginClassLoader.class).error(e);
      return null;
    }
  }

  private static Method getFindResourceMethod(final Class<?> clClass, final String methodName) {
    try {
      final Method declaredMethod = clClass.getDeclaredMethod(methodName, String.class);
      declaredMethod.setAccessible(true);
      return declaredMethod;
    }
    catch (NoSuchMethodException e) {
      final Class superclass = clClass.getSuperclass();
      if (superclass == null || superclass.equals(Object.class)) {
        return null;
      }
      return getFindResourceMethod(superclass, methodName);
    }
  }

  public PluginId getPluginId() {
    return myPluginId;
  }

  @Override
  public String toString() {
    return "PluginClassLoader[" + myPluginId + ", " + myPluginVersion + "]";
  }
}